João Alberto Passos Filho

Parallel computing applied to the stochastic dynamic programming for long term operation planning of hydrothermal power systems

In this paper, parallel processing techniques are employed to improve the performance of the stochastic dynamic programming applied to the long term operation planning of electrical power system. The hydroelectric plants are grouped into energy equivalent reservoirs and the expected cost functions are modeled by a piecewise linear approximation, by means of the Convex Hull algorithm. In order to validate the proposed methodology, data from the Brazilian electrical power system is utilized.

A new approach for area interchange control modeling

This paper describes a new methodology to evaluate the area interchange control (AIC) in a power flow problem using the Newton-Raphson method. In this methodology, the equations of the AIC are incorporated into the system of equations of the power flow problem. Thus an augmented system of equations, which is linearized and solved, at each iteration, is obtained. The proposed method has been tested and compared with existing methods in the literature using both small and large scale systems. The results presented validate the proposed technique.

Power system stabilizers tuning using bio-inspired algorithm

This paper presents a methodology for coordinated tuning of power system stabilizers taking into account a set of pre-specified operating conditions. The tuning procedure is formulated as an optimization problem which aims to maximize the system damping ratio. The proposed methodology is based on the bio-inspired Modified Cuckoo Search method. The methodology is applied for coordinated stabilizer tuning to New England test system. The results obtained are compared with a genetic algorithm approach.

Modelo para o despacho de usinas individualizadas no planejamento hidrotérmico de médio prazo baseado em PNL

This paper presents a method to the hydrothermal dispatch using optimization techniques based on non linear programming techniques. To do so, the expected cost-to-go functions from a long term operation plannning strategic decision model are used. This decision model is based on stochastic dual dynamic programming and energy equivalent reservoirs. The proposed method considers a set of historical water inflow scenarios to the hydroelectric reservoirs. Those scenarios are used to simulate the long term operation planning to a given horizon. The results obtained from this disaggregation model (MIUH) are compared with those from the model officially adopted in the Brazilian power system, SUISHI-O. The latter is based on operation heuristics aiming at operating the reservoir maintaining the water storag e in similar levels, that is, trying to operate them in parallel.

Parallel Transient Stability Simulation Based on Multi-Area Thévenin Equivalents

In this paper the diakoptics-based branch-tearing method for solving large electric networks, known as the Multi-Area Thévenin Equivalents (MATE), is combined with the alternating method for parallelizing the transient stability simulations of bulk power systems. In the proposed framework, equations associated with dynamic and static devices and passive network are distributed among computing processes. The paper discusses an implementation of the parallel transient stability simulator along with results for two power systems with about 4,000 and 15,000 buses, both based on the Brazilian Interconnected Power System. Performance metrics for assessing the effectiveness of the proposed methodology are also presented and discussed. In order to validate the implementation, the results are also compared with those from an industrial-grade transient stability program, ANATEM developed by CEPEL.

Comparison among methodologies for identification of pilot buses and its impact on the steady state secondary voltage control

This paper presents a comparison analysis among some methodologies in which aims to solve the selection of pilot buses for Secondary Voltage Control. For this purpose, a brief review of methodologies for both identifying voltage control areas and pilot buses selection are described. The validation of the results is done through the standard deviation applied to the variation of the voltage magnitude of the system buses before and after a given disturbance, reactive power generation and active power transmission losses. In this paper, the disturbance is the application of a load curve applied in reactive power demand of the load buses consists of 168 load levels. Results are presented using the well known IEEE 118 buses system.

Advanced SVC models for Newton-Raphson load flow and Newton optimal power flow studies [discussion and closure]

Two sets of authors provide separate comments on the paper by H. Ambriz-Perez et al. (see ibid., vol.15, no.1, p.129-36, 2000). The original authors reply to the comments.

A full Newton approach to consider reactive power generation limits in power flow problem using sigmoid switches

In this paper, a new full Newton methodology to represent the reactive power generation limits in the Power Flow problem is proposed. This approach consists of using a set of Sigmoid Switches that incorporates new equations into the problem formulation. Thus, the equations representing the reactive power limits are incorporated into the Jacobian Matrix. The terminal voltage and the reactive generation of each generator are the new variables and are obtained directly by the Newton method. A review of the traditional methodology for modeling the limits of reactive generation in power flow formulation is as well done. The proposed methodology is validated through the study of two test systems. The first system is the IEEE 14-bus test system and the second one is the 39-bus New-England power system. The results presented are validated with the ANAREDE program and showed the proposed methodology effectiveness.

A memetic algorithm for power system damping controllers design

This paper presents a hybrid algorithm for robust and coordinated design of power system stabilisers. Power system stabilisers are controllers installed on synchronous generators for excitation control in order to damp power system oscillations. The tuning procedure (gain and phase compensation stage) is cast as an optimisation problem which aims at maximising the damping coefficients in closed-loop operation. Robustness is dealt with by using multiple operating scenarios. For the optimisation problem solution, the bio-inspired Bat Algorithm is combined with the steepest descent method for local search capability enhancement. The proposed algorithm is applied to benchmark systems for validation.

An affine arithmetic method to identify Voltage Control Areas for Secondary Voltage Control

This paper aims to present a methodology to identify Voltage Control Areas (VCA) for Secondary Voltage Control (SVC). The proposed methodology consists in the representation of data uncertainty using Affine Arithmetic (AA) applied to the Power Flow Analysis. The uncertainty used in this paper is associated only with reactive power demand, mainly due to forecast errors. The IEEE 14 bus test system and the IEEE 118 bus system are used to evaluate the proposed methodology and the results presented validate and indicate the effectiveness of using an AA-based method to identify VCA.